Cross-flow fluid bed reactor

ABSTRACT

Apparatus for beneficiating titaniferous ores to produce essentially pure titanium dioxide by alternatingly contacting the ore at a temperature of 700* to 1250*C with carbon monoxide for a short period of time and then chlorine for a short period of time and then repeating the alternate steps of contacting the ore with carbon monoxide and chlorine, said apparatus comprising a fluid bed reactor containing a bed support consisting of a perforated plate or fritted disc beneath which is a compartamentalized gas plenium chamber, each compartment of the chamber being served by a gas feed line whereby sequential and alternating zones of carbon monoxide and chlorine are encountered by the ore proceeding through the fluidized bed, an overhead outlet tube by which gases are exhausted from the reactor, and a side outlet port by which the solid product is removed.

United States Patent 11 1 Dunn, Jr. 1 1 Jan. 30, 1973 541 CROSS-FLOWFLUID BED REACTOR 2,371,619 3/1945 Hartley; ..75/26 ux 2,557,528 6 1951Andrews ..23 202 R x [76] Inventor Wendell f 3,120,999 2/1964 Rummeny et61.. ..23 202 R Street, y y Australla 3,300,295 1/1967 BOUClBUl et al...75/26 x Oct- 21 3,433,624 BOUCl'flUI et al. X

[21] Appl. No.: 82,337 Primary ExaminerBarry S. Richman Attorney-SamuelV. Abramo [52] US. Cl ..23/284, 23/202 R, 75/26,

. 75/33266/24 57 ABSTRACT [51] Int. Cl. ..B01j l/00, C01g 23/04, C221)1/10 Apparatus for beneficiating titaniferous ores to [56] ReferencesCited UNITED STATES PATENTS 2,501,487 3/1950 Whitman ..34/57 C 2,586,8182/1952 Harms ....23/284 UX 2,641,849 6/1953 Lintz ..34/57 C 2,782,0192/1957 Turney et a1. ..,.23/284 X 3,042,498 7/1962 Norman ....23/284 X3,539,293 11/1970 Boucraut et al...... ....23/284 X 3,582,288 6/1971Taylor et a1. ..23/284 1,528,319 3/1925 Carteret et al.... ..23/202 R1,542,350 6/1925 Whittemore ..23/202 R X 1,789,813 1/1931 Gaus....23/202 R UX 2,184,884 12/1939 Muskat et a1. ....23/202 R X 2,184,88512/1939 Muskat et a1. ..23/202 R X produce essentially pure titaniumdioxide by alternatingly contacting the ore at a temperature of 700 to1250C with carbon monoxide for a short period of time and then chlorinefor a short period'of time and then repeating the alternate steps ofcontacting the ore with carbon monoxide and chlorine, said apparatuscomprising a fluid bed reactor containing a bed support consisting of aperforated plate or fritted disc beneath which is a compartamentalizedgas plenium chamber, each compartment of the chamber being served by agas feed line whereby sequential and alternating zones of carbonmonoxide and chlorine are encountered by the ore proceeding through thefluidized bed, an overhead outlet tube by which gases are exhausted fromthe reactor, and a side outlet port by which the solid product isremoved.

10 Claims, 5 Drawing Figures SHEET 10F 2 PATENTEDJM 30 1915 INVENTORWendelLEDamJr:

ATTORNEY PATENTEDJANIiO ma 3. 71 3. 781

SHEET 2 OF 2 3 Wendell E.Durm,fi:

ATTOBNL'Y CROSS-FLOW FLUID BED REACTOR BACKGROUND OF THE INVENTIONfurnaces. Such reactors have disadvantages connected I with the particlesize-reaction velocity relationship as well as temperature-corrosiveatmosphere relationships. Some of these problems have been solved by useof fluid-bed reactors.

However, where extensive removal of an impurity, or reaction to anextreme degree is required, it is ordinarily necessary to use amulti-stage fluid-bed reactor. In a fluid-bed process requiring multiplestages such as the beneficiation of ilmenite in which iron removal ofgreater than about 95 percent is desireable, the ilmenite is reactedstep-wise in several stages in which the gas flow is counter-current tothe solids flow. Such a reaction incurs extreme heat losses at hightemperatures and gas distribution is complicated by the corrosive actionof the reaction gases and entrained solids on many materialsof'construction.

I have discovered that the apparatus of this invention, which employscross-current action between solids and gases, and sequentialintroduction of reactive gases, results in simplified gas distribution,improved gas-solid contact, improved separation of feed and productstreams, and reduced corrosion even at high reaction temperatures.

SUMMARY OF THE INVENTION In summary this invention is directed to across-current fluid bed reactor for the beneficiation of titaniferousores at a temperature of 700 to 1250C with carbon monoxide and chlorinecomprising a. a reaction chamber having 1. a solids inlet at oneextremity; and 2. a solids outlet and a gas outlet at the otherextremity; b. a bed support positioned within the chamber to receive thesolids comprising 1. a support means; and 2. a plurality of gas inletsin the support means;

and 3. a gas plenum chamber beneath the bed support comprising 1. aplurality of separate compartmentscommunicating with the bed support bymeans of the gas inlets in the supportive means; and 2. each compartmentbeing served by a gas feed line; whereby sequential and alternatingzones of carbon monoxide and chlorine gases can be passed through thebed in a direction across the current of flow of solids moving laterallyalong the bed, said solids being maintained in fluid state by saidreactive gases.

This apparatus provides a fluid-bed reactor in which titaniferous orecan be reacted at 700 to 1250C with carbon monoxide and chlorine in asequential alternating manner to obtain essentially complete reaction ofthe iron oxideand other metal oxide impurities in the ore at reducedcost through improved gas-solid contact and reduction of corrosion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an axial cross-section of areactor of this invention wherein ore can be reacted with reactant gasessequentially as described hereinafter.

FIG. 1A is an axial cross-section of a hopper-receiver whichcanbeemployed with the reactor of FIG. 1 in place of the solidscollector.

FIG. 2 is an axial cross-section of another reactor of 0 this inventionwherein the solids flow in the bed is implemented by gravity.

FIG. 3 is an axial cross-section of another reactor of this inventionwherein the multiple chambers containing only one reactive gas arepreceded by a chamber in which mixed reactive gases are fed.

FIG. 4 is a sectional view across the reactor of FIG. 3 at line 2--2.

DESCRIPTION OF THE INVENTION This invention relates to a cross-currentfluid-bed reactor for reacting titaniferous ores at 700 to 1250C withcarbon monoxide and chlorine in an alternating, sequential manner.

As stated above, the reactor of this invention comprises a reactionchamber, a bed support, and a compartmentalized gas-plenum chamber. Inone end of the reaction chamber an inlet provides means for solids feedand two outlets at the other end of the reaction chamber provide meansfor separate gas and solids removal. The bed support bears the fluidizedsolids and contains a multiplicity of openings communicating with thegas plenum chamber whereby reactive and fluidizing gases are introducedinto the reaction chamber.

Referring to FIG. 1, ore is introduced into the reactor 1 through inlet2. The ore is supported on the support means 3 to form a bed 4. Thesupport means can be for example a perforated plate of fitted disc. Thesupport means contains a plurality of gas inlets 5, preferably 1/32 to3/32 inch in diameter. The ore is agitated and fluidized by reactantgases introduced through gas inletsvia the gas plenum chambers 6 and thegas feed lines 7. Gaseous products consisting primarily of ironchlorides, other metal chlorides, car? bon monoxide and any diluentgases, are withdrawn from the reactor via the gas outlet tube 8. Thesolid product, consisting primarily of titanium dioxide is retained inthe reactor to the desired depth by means of a weir or dam 9 whichpreferably is 0.5 to 2 feet in height and upon overflow is conveyed viathe solids outlet 10 to a storage facility 11. Alternatively, a hopper12 shown in FIG. 1A, can receive the beneficiated product where it isallowed to cool. The hopper can be emptied such as by means of a valve13, and the product can be conveyed to a magnetic separator (not shown)to remove partially beneficiated ore containing greater than 1.0 percentby weight of Fe O FIG. 2 shows a reactor of this invention similar tothat of FIG. 1, except the support means 3 is arranged such that thefluidized bed 4 has a depth gradient towards the solids outlet 10 ofabout 2 inches at the point of ore inlet to about 2 feet at the solidsoutlet for beneficiating ores by a uniform rate of flow of gases. Thisapparatus is useful.

FIG. 3 shows a reactor of this invention similar to that of FIG. 1,except the gas chambers 6 for each of the reactive gases is preceded bya single chamber 14 in which a mixture 15 of chlorine and carbonmonoxide are fed to the fluid bed. Alternatively, the final chamber canbe used to convey oxygen or air through the bed to burn off carbon whichcan be added to the ore mixture.

FIG. 4 shows a cross-sectional view of the reactor of FIG. 3; takenacross the line 4-4.

Reactor operation Titaniferous ore is fed to the reactor of thisinvention through a feed inlet and is supported on perforated supportivelevel. The ore bed is fluidized by streams of reactive gases,alternately carbon monoxide, then chlorine, then carbon monoxide, thenchlorine, etc. for the length of the reactor. If desired, additionaldiluent gases such as oxygen, air, nitrogen or excess carbon monoxidecan be used along with the reactive gases to keep the orebed in afluidized state and control the temperature. By this reaction sequencethe iron content of the ore can be reduced to 0.2 percent by weight orless and essentially pure titanium oxide is produced. Generally speakingthree carbonylation-chlorination cycles are desirable to achievesufficient reduction of the iron content of the ore, and more than 20are unnecessary. Preferably 4 to 12 cycles are preferred.

The feed rate of the reactive gases is balanced with that of diluentgases, if used, so as to maintain the ore bed in a fluidized state.Additionally, the feed rate of the reactive gases is controlled suchthat most of the gases are reactively consumed in the ore'bed. Dependingupon the depth of the ore bed, which is ordinarily between about 0.1 andfeet, the rate of flow of carbon monoxide and chlorine are usuallybetween about 0.19 and 2.0 cubic feet per second. A preferred depth forthe ore bed is about 0.1 to 1 foot and a preferred flow rate for thereactant gases is about 0.19 to 1.25 cubic feet per second.

The width and length of the reactor can vary widely. For example, thewidth can be up to 2 to 15 feet or wider. Preferably, the width is 5 to10 feet. The length can also vary greatly depending upon the number ofcompartments used. For example the length can be 5 to 30 feet or longerand preferably is 10 to feet.

The retention of ore in the reactor can be controlled by both feed rate,the width and length of the reactor and bed depth with the lattervariable in accordance with weir or dam height. Bed depth control allowsretention time variation of either the gases or solids by increasing ordecreasing the bed depth at the product end. .The bed depth need not beheld constant, and by tilting the support means as in FIG. 2 either endmay be made deeper with corresponding increased retention time in thatsection. By using a support means with other than a linear shape, theretention time in any section of the bed can be varied.

The introductory rate of gases described above ordinarily produces aflow rate of hot gases through the reactor of about 0.25 cubic feet persecond, however lower or higher rates are operable.

It is preferable that the ore being used have an average particle sizeof at least 20 mesh and preferably 90 percent of the ore is 75 mesh.However ore of larger or smaller particle size can be used in thereactor of this invention.

The reactor is operated at a temperature ranging from about 700C to ashigh as 1250C or higher. It is preferred to keep the maximum temperatureat about ll50C and the most preferred temperature range is between 950and l050C.

The product of this process is essentially pure, iron oxide-free,titanium dioxide. The titanium dioxide content of the product isordinarily percent, by weight, or higher and iron oxide content isordinarily 1.0 percent, by weight, or less. The product may also containsmall amounts of heavy metal oxides, generally less than 0.2 percent byweight, with the remainder being non-chlorinatable silicates and thelike.

Materials of Construction The reactor is fabricated ofcorrosion-resistant materials well known to the art such as quartz, aceramic such as fire brick or the like, preferably, capable ofwithstanding contact with, singly or in mixtures, chlorine, titaniumtetrachloride, ferrous and ferric chlorides, carbon monoxide and oxygenat temperature as high as 1250C and higher. Other portions of theapparatus are similarly fabricated of materials known to the art to besuitable for the use to which they are put here. For example the gasplenium chamber is ordinarily divided with the same materials used inthe reactor and the gas inlet pipes can be a ceramic material or acorrosion resistant metal. The product storage facility or hopper can bemade of materials such as ceramic, concrete or metal.

As stated above, the apparatus of this invention is suitable for use inbeneficiation of titaniferous ores. Titanium dioxide produced in theapparatus of this invention is less porous than titanium dioxideproduced in prior art processes and contains a smaller amount of fines.As a result there is a decrease in the loss of titanium values inproducts prepared in the apparatus of this invention as compared withthose of the prior art.

The following example further illustrates this invention.

The reactor of FIG. 1 having the weir set to form a bed depth ofl.0'foot, a length of 3 feet and a width of 9 feet was used tobeneficiate a titaniferous ore obtained from Queensland, Australia andhaving, by weight, the following composition:

TiO, 54% FeO 21% Fe,0, 21% inert and remainder other oxides The ore hada particle size distribution as follows:

+60 mesh 0.04 percent. by weight -60+85 17.7 -8S+l 00 49.7 l00+l20 21.4--l20 8.3

The reactor is heated to l000C. The rate of addition of the ore, carbonmonoxide and chlorine to the reactor was adjusted to correspond to aflow rate through the hot ore bed of 0.25 cubic feet per second.

The product contained about 95 percent, by weight, TiO and 1.0 percent,by weight, ofiron oxide.

The reactor of FIG. 2 is another modification of my invention utilizingthe concept that the rate of reaction of the beneficiation decreases asthe iron content decreases. This device overcomes this problem bypresenting to the reactant gases a greater amount of iron by increasingthe bed depth.

The foregoing detailed description has been given for clarity ofunderstanding only and no unnecessary limitations are to be understoodtherefrom. The invention is not limited to the exact details shown anddescribed for obvious modifications will occur to those skilled in theart.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. A cross-current fluid-bed reactor for the beneficiation oftitaniferous ores at a temperature of from 700 to 1250C, comprising:

a. a horizontally disposed reaction chamber having 1. a solids inlet atone horizontal extremity; and

2. a solids outlet means and a gas outlet at the other horizontalextremity;

b. a bed support positioned within the chamber to receive theparticulate titaniferous ore solids comprising:

l. a support means; and

2. a plurality of gas inlets in the support means;

c. a source of a gaseous reducing agent;

d. a source of a gaseous halogenating agent;

e. a gas plenum chamber beneath the bed support comprising:

1. a plurality of separate compartments communicating with the bed oftitaniferous ore solids by means of the gas inlets in the support means;and

2. each compartment being served by a separate gas feed line; and

f. conduit means connecting some of said separate gas feed lines to saidsource of gaseous reducing agent and connecting the balance of saidseparate gas feed lines to said source of gaseous halogenating agent,said connections being such as to provide adjacent plenum compartmentswith gas from separate sources; whereby sequential and alternating zonesof reducing and halogenating gases can be passed through the bed in adirection across the current of flow of solids moving laterally alongthe bed, said solids being maintained in a fluidized state by saidgases.

2. The apparatus of claim 1 wherein the gas inlets in the bed supportare l /32 to 3/32 inch in diameter.

3. The apparatus of claim 1 having a width of 2 to 15 feet, a length of5 to 30 feet and means for retaining solids to a depth of 2 inches to 2feet.

4. The apparatus of claim 1 wherein the gas plenum chamber contains from3 to 20 compartments each communicating with the bed of solids.

5. The apparatus of claim 1 wherein the solid outlet means is a weirwhereby the depth of the ore bed is controlled.

6. The apparatus of claim 1 wherein the gas plenum chamber contains from3 to 20 compartments each for reducing agent and halogenating agent.

7. The apparatus of claim 6 wherein the gas plenum chamber contains for4 to 12 compartments each for reducing agent and halogenating agent.

8. The apparatus of c arm 1 wherein the bed support

1. a plurality of separate compartments communicating with the bed oftitaniferous ore solids by means of the gas inlets in the support means;and
 1. a support means; and
 1. a solids inlet at one horizontalextremity; and
 1. A cross-current fluid-bed reactor for thebeneficiation of titaniferous ores at a temperature of from 700* to1250*C, comprising: a. a horizontally disposed reaction chamber having2. a solids outlet means and a gas outlet at the other horizontalextremity; b. a bed support positioned within the chamber to receive thepartiCulate titaniferous ore solids comprising:
 2. a plurality of gasinlets in the support means; c. a source of a gaseous reducing agent; d.a source of a gaseous halogenating agent; e. a gas plenum chamberbeneath the bed support comprising:
 2. The apparatus of claim 1 whereinthe gas inlets in the bed support are 1/32 to 3/32 inch in diameter. 2.each compartment being served by a separate gas feed line; and f.conduit means connecting some of said separate gas feed lines to saidsource of gaseous reducing agent and connecting the balance of saidseparate gas feed lines to said source of gaseous halogenating agent,said connections being such as to provide adjacent plenum compartmentswith gas from separate sources; whereby sequential and alternating zonesof reducing and halogenating gases can be passed through the bed in adirection across the current of flow of solids moving laterally alongthe bed, said solids being maintained in a fluidized state by saidgases.
 3. The apparatus of claim 1 having a width of 2 to 15 feet, alength of 5 to 30 feet and means for retaining solids to a depth of 2inches to 2 feet.
 4. The apparatus of claim 1 wherein the gas plenumchamber contains from 3 to 20 compartments each communicating with thebed of solids.
 5. The apparatus of claim 1 wherein the solid outletmeans is a weir whereby the depth of the ore bed is controlled.
 6. Theapparatus of claim 1 wherein the gas plenum chamber contains from 3 to20 compartments each for reducing agent and halogenating agent.
 7. Theapparatus of claim 6 wherein the gas plenum chamber contains for 4 to 12compartments each for reducing agent and halogenating agent.
 8. Theapparatus of claim 1 wherein the bed support is tilted to give a deeperbed at the solids outlet.
 9. The apparatus of claim 8 wherein the gasplenum chamber contains 3 to 20 compartments each communicating with thebed of solids.